The present embodiments relate generally to medical devices, and more particularly, to apparatus and methods for maintaining a force upon tissue using a loop member.
There are various instances in which it may become necessary or desirable to deliver a deployable snare into engagement with tissue. For example, such a snare may be used to induce hemostasis during a polypectomy, esophageal variceal bleeding, gastric variceal bleeding, and the excision of gastrointestinal stromal tumors. Further, deployable snares may be useful in ligation of varices or polyps, closure of gastrointestinal fistulas, and other procedures.
There are various commercially available deployable snares. Some of the deployable snares comprise a loop made of nylon, one or more elongated wires, sutures and/or other materials. The size and configuration of the loop may be adjusted using a stopper or cinching member that may be sized to surround first and second ends of the loop. As the stopper or cinching member is distally advanced relative to the loop, the size of the loop may be decreased and a desired amount of force may be imposed upon target tissue.
While such snares are beneficial for providing an initial pressure upon the target tissue, the diameter of the loop generally remains fixed in the original configuration applied by the physician. In particular, the stopper or cinching member maintains the original diameter and configuration of the loop. It has been discovered by the applicants that, as tissue begins to necrose, the shape of the tissue originally enclosed by the loop may change profile, and in particular, may decrease in size. Therefore, if the loop remains in its original fixed configuration, the loop may prematurely fall off of the tissue and fail to maintain a continuous force upon the tissue over an extended period of time.